Objective: Osteometric studies using individual bones have been a topic of interest among researchers. Such researches are a tool for conducting studies related to evolution, demographic profiles and forensic sciences. Skull is important in this regard as it resists adverse environmental conditions over time. The mastoid process can thus be used as a marker of sex as well as ancestry of individuals and populations. The aim of this study was to evaluate the use of mastoid process as a tool for sex determination in unidentified skeleton. Materials and Methods: 70 (44 male and 26 female) complete undamaged skulls of known sex were used for the study. Mastoid length was recorded on the right and left mastoid process in each skull. Measurements were made with a digital vernier caliper. Results: Statistics revealed high significance (p<0.0001) for the mastoid length for sex determination. Conclusion: Reports on the use of mastoid process as a tool for sex estimation in unidentified human skeleton have been reported in different populations. The present study supports this finding among the Indian population. DOI: http://dx.doi.org/10.3126/ajms.v6i6.12406 Asian Journal of Medical Sciences Vol.6(6) 2015 93-95